The quality of MR angiography (MRA) images depends on
synchronizing data acquisition with arrival of the contrast bolus in the
vessels of interest. In this study we analytically verify that the circulatory
system can be modeled as a linear time-invariant system that responds linearly
to the infusion as its input. We further show how such a system may be characterized
based on physiological parameters. This approach was experimentally quantified
for MRA by implementing a software tool. The implemented algorithm as well as
the signal enhancement in the high-resolution MRA, predicts stable 85% peak
periods for carotid and venous signals.